The invention relates to a slot sealing material for an electric machine, which for accommodating an electric conductor arrangement comprises at least one slot having a slot opening, containing a magnetic filler, in particular a soft-magnetic filler, and a reaction resin mixture comprising at least a resin component and a curing agent component, which are present separately prior to processing. The invention further relates to a slot seal and a method for producing a slot seal for an electric machine.
The slots of electric machines serve to accommodate insulated electric conductors or conductor arrangements. They generally have a slot opening, via which the conductors or conductor arrangement are inserted into the slot. In particular in the case of high-voltage machines, so-called “open slots” are used, wherein the slot opening extends across the full width of the slot. The slot opening must hence be sealed after insertion of the electric conductor or conductor arrangement, in order to prevent the conductors from rising up out of the slot during operation of the electric machine.
The slot seal for such slot openings is normally executed with solid sealing bodies, known as slot wedges. These slot wedges are e.g. manufactured from technical laminated materials using mechanical processing. Alternatively they can be manufactured from thermoplastic or duroplastic molding compounds using extrusion or injection molding.
To improve the magnetic flux field in the region of the slot opening, the slot seals are in part designed to be soft-magnetic. In this case the slot seals are designed in the form of slot wedges, made of iron-filled laminated materials. Such a soft-magnetic slot seal is however normally bonded to the slot, in order to achieve a good wringing fit. Otherwise there is a risk that the slot wedge will work loose because of the operating stresses (thermal stress, thermomechanical alternating stress, magnetic alternating stress, environmental influences). This bonding can only be reliably executed with considerable effort.
A prefabricated sealing body which is used as a slot seal is described e.g. in WO 2006/100291 A1. The sealing body in this case consists of a material with a thermoplastic polymer material and a magnetic filler.
Another form of soft-magnetic slot seal is thermosetting epoxy resins filled with iron powder, as described e.g. in unexamined patent applications DE 1 288 186 and DE 1 299 357. The epoxy resins are pressed into the slot opening as paste-like compounds and are then thermally cured. Such a slot seal is distinguished by a permanent wringing fit compared to the soft-magnetic wedges.